1. Field of the Invention
The present invention generally relates to state transition control systems and, more particularly, is directed to a transition control system for use with a recording and/or reproducing apparatus such as a video tape recorder in which state transition control is carried out sequentially and with a lot of time.
2. Description of the Prior Art
In the prior art, control in which state transitions are executed sequentially and with a lot of time is typically executed by a video tape recorder (VTR) shown, for example, in FIG. 1 as follows.
Initially, an arrangement of this VTR will be described. In this example, as shown in FIG. 1, a microcomputer 2 having programs for operation input processing, state decision processing and state transition control processing is connected with a keyboard 4, a remote controller input unit 6, an editor input unit 8, a mechanism unit 10, a servo circuit 12 and a video-audio signal circuit 14.
As the control done by the microcomputer 2 thus arranged, i.e., control in which state transition is executed sequentially and with a lot of time, ordinary processing is carried out. The ordinary processing is composed of a routine control for a bus line and detection of state transition factor, The routine bus line control is for communication processing among respective ICs (integrated circuits) of an external bus line, an interface, a character generator, a video signal processing unit or the like, and a LCD (liquid crystal display) drive microcomputer and so on. The detection of a state transition factor is authentication of any of the following: input information from the keyboard 4, the remote controller input unit 6, the editor input unit 8, detection of a tape top or tape end of a video tape from the mechanism unit 10 or the servo circuit 12.
The above-mentioned control done by the microcomputer 2 further includes a processing during state transition and, in this processing during state transition, the afore-said ordinary processing is executed and the switching of the respective circuits and the state transition processing of the mechanism unit 10 are executed sequentially. When the VTR is set in the playback mode from the stop mode (STOP), for example, a rotary head drum having magnetic heads mounted thereon is rotated and then the corresponding part of the mechanism unit 10 is changed from the stop mode to the video tape transport mode. Further, a capstan is rotated, the rotary head drum and the capstan are servo-controlled and the video-audio signal processing unit 14 is actuated in playback mode, thereby video and audio signals being reproduced. In this case, the VTR is set in the state transition standby mode of several seconds at every processing. This ordinary processing includes a loop processing of steps shown in FIG. 2 as a main routine.
The processing during state transition is comprised of state transition interrupt processings which utilize an interrupt function such as a timer interrupt or the like as shown in FIGS. 3A, 3B, a pointer processing of the state transition which is inserted into the main routine by utilizing a pointer as shown in FIG. 4, processings utilizing separated stacks wherein the processing utilizing a stack for the state transition provided separately is executed as shown in FIGS. 5A and 5B, and an independent state transition processing wherein the ordinary processing during the state transition is cut as shown in FIG. 6.
According to the conventional state transition control system, however, in case of executing these processings, a lot of ROMs, RAMs and stacks are required, and further the organizing processings of the interruptions, pointers and stacks are complicated, so that erroneous operations are often caused. Further, when ordinary processing is not executed during state transitions, operations such as selection of functions of the mechanical unit or the like by an operator (that is, a so-called man-machine interaction) can not be performed during the state transition processing, which results in the operability of the device being degraded greatly.